What exactly did yesterday’s HTC-wide Windows Phone 7 update accomplish? Some users didn’t notice any changes at all. Reader Glueharbour reported a fix for camera handling in sleep mode and a general data speed boost when using WiFi for data. With as small as these changes are, we wouldn’t be surprised if there are even more tweaks that just haven’t been spotted yet. There’s a chance, though, that things have changed for the worse, as some owners of HTC smartphones have reported that they appear to now be using a lower bit depth for their graphics.

The problems apparently crop up once phones are running firmwares FW 2250.09.11001 and FW 2250.09.12000. Affected smartphones display noticeable color banding in images with gradual shift in tone. With 24-bit graphics, you would see a smooth gradient, but post-update it looks like things are in 16-bit mode, with abrupt shifts between colors.

WMPoweruser is conducting an informal poll, with about 70% of HTC Windows Phone 7 users noticing the change. We hope whatever’s causing this is due to an oversight, rather than an intentional choice on HTC’s part, and it will take steps to restore previous image quality. It would be awful for users to have bought phones with bright, colorful screens only to have them disabled in software.